linux-kernel - Re: [PATCH 1/2] sched/idle: Fix arch_cpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201201110209.GQ3040@hirez.programming.kicks-ass.net>
Date:   Tue, 1 Dec 2020 12:02:09 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     rafael@...nel.org, viresh.kumar@...aro.org, mingo@...nel.org,
        x86@...nel.org, mark.rutland@....com, will@...nel.org,
        svens@...ux.ibm.com, linux-kernel@...r.kernel.org,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH 1/2] sched/idle: Fix arch_cpu_idle() vs tracing

On Mon, Nov 30, 2020 at 01:00:03PM -0800, Guenter Roeck wrote:
> On Fri, Nov 20, 2020 at 12:41:46PM +0100, Peter Zijlstra wrote:
> > We call arch_cpu_idle() with RCU disabled, but then use
> > local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.
> > 
> > Switch all arch_cpu_idle() implementations to use
> > raw_local_irq_{en,dis}able() and carefully manage the
> > lockdep,rcu,tracing state like we do in entry.
> > 
> > (XXX: we really should change arch_cpu_idle() to not return with
> > interrupts enabled)
> > 
> 
> Has this patch been tested on s390 ? Reason for asking is that it causes
> all my s390 emulations to crash. Reverting it fixes the problem.

My understanding is that it changes the error on s390. Previously it
would complain about the local_irq_enable() in arch_cpu_idle(), now it
complains when taking an interrupt during idle.